This invention relates to machines for making nonwoven bonded carpeting and, more particularly, to the portion of such a machine that folds the yarn from which the pile is formed and either plants the yarn in the bonding material in which it is anchored or arranges the yarn so that the bonding material can be applied later.
Machines have been developed for making carpeting by folding a number of strands of yarn in a row simultaneously and planting them in a layer of adhesive spread across the surface of a sheet of backing material, and then repeating the operation on an opposing parallel sheet of backing material. This is done to form a series of accordion-type loops from each strand of yarn between the backing layers. After the adhesive has been cured, the loops are severed midway between the backing layers to form two separate carpets.
Another type of machine has been developed in which the loops of yarn are formed initially without bonding them to the backing layers, and the adhesive is applied later to the yarn. In both types of machines the adhesive can be used as the backing layer in addition to being the means for anchoring the yarn in place.
When a backing material is used, it is normally formed of woven strands of jute, although there are many other suitable types of backing material. The bonding material can be an adhesive such as a liquid synthetic resin which has been applied to the backing sheets or directly to the yarn. Polyvinylchloride (PVC) has been found to be effective.
A number of different types of mechanisms have been developed for embedding the yarn into bonding material. As taught by U.S. Pat. No. 3,531,343 to Couquet, individual strands of yarn can be planted one-by-one into an advancing sheet of backing material coated with an adhesive. The lower end of each strand is clamped and cut the desired length. The severed portion is then lowered by the clamping apparatus and planted into the adhesive. This system for manufacturing nonwoven carpeting is disadvantageous for several reasons. First, because each individual strand has to be clamped, severed and lowered into place, much time is wasted by separately performing each one of these steps. In addition, because of the space taken up by the clamping mechanism and other elements used in the planting process, there is a physical limitation upon the number of strands that can be planted per square inch, thereby limiting the gauge of the carpet pile.
Several machines have been developed which use blade-like members that extend across the entire width of the sheet of backing material for folding the strands of yarn and pushing them into an adhesive layer. One such machine is shown in U.S. Pat. No. 3,127,293 to Trenteseaux, which provides a blade and a series of superimposed plates for alternately urging the strands of yarn against adhesive that is coated on a pair of packing strips at a point near the top of the well into which the backing layers are advanced. A pair of metal foils is provided for cooperating with the blade and plates so that the strands of yarn are folded in a way to prevent an excessive length of the yarns from becoming embedded in the adhesive layer. However, problems arose with this machine because it proved to be too slow since each member that presses against the strands of yarn must be completely withdrawn before the other member can be moved into place to form the next loops of accordion-type chains. In addition, the operation of the machine is such that the members tended to become coated with the adhesive and had to be cleaned periodically, thereby necessitating closing down the machine and stopping production.
Some of these problems were apparently solved by the machine in U.S. Pat. No. 3,657,052 to Debonnet, where a different mechanism that includes a pair of blades is provided for folding and planting the yarn. Each blade operates to hold the yarn in position in the adhesive for a short time while the second blade moves toward its bonding position so that the yarns will not be pulled out of the adhesive. This delaying action is accomplished by means of cam surfaces which operate to retract the blades along paths different from those along which they were advanced. However, although this mechanism is an apparent improvement over the one in the Trenteseaux patent, the blade that holds the planted yarns in place is not delayed long enough, which results in some of the yarns being pulled out of the adhesive during the next planting step. In addition, the blades and their movement require highly complex equipment that includes a number of heavy, expensive and space-consuming components. Much energy is required to operate the machine which is extremely expensive to manufacture and operate. Because of the large number of moving parts and their relatively large size, the machine is limited in its operational speed.